n Process by which a film is applied mechanically to sheet metal. The machine consists of a series of horizontal cylindrical rollers. The coating is picked up by one of the first rollers rotating in a trough containing the coating, is transferred to subsequent rollers until evenly distributed over the last roller, and thence to the flat surface of mild steel, tinned iron, or other suitable sheets. Application of paint by means of a hand-operated roller to wall surfaces, etc. The process of coating substrates with liquid resins, solutions, or dispersions by contacting the substrate with a roller on which the fluid material has been spread. The process is often used to apply a contrasting color or raised lettering or markings. See also Gravure Coating and Reverse-Roll Coating ((1976) Printing ink handbook. National Association of Printing Ink Manufacturers).